Although there is no routine procedure for determination of serum markers in patients with malignant melanoma (MM), some markers are being studied as potentially useful prognostic tools. Serum lactate dehydrogenase (LDH), protein S-100B, melanoma-inhibiting activity (MIA) and tyrosinase may correlate with melanoma progression. In this study, the results of determination of S100 protein, LDH, MIA and tyrosinase in the serum of 50 patients with MM (stages I-IV) were determined. The increased values of MIA were found in 26% patients in stage I, while in 50% patients in stage IV Increased S-100 protein was found in 13% patients in stage I while in 50% patients in stage IV. The increased values of LDH were found in 26% patients in stage I, while in 25% patients in stage IV. The positive serum tyrosinase was noticed in 17.3% patients in stage II, while in 25% patients in stage IV. The obtained results have revealed no significant differences between the groups in higher and lower stages of the disease, indicating that blood markers are not reliable prognostic factors for MM progression.